Timing apparatus



March 7, 1944. T, B, GIBBS 2,343,452

TIMING APPARATUS Filed Aug. 11. 1941 fg z [.Z/ Stcuzdezfd flea. I i vINVENIOR.

\ fiofizas 3 63619175 BY W Patented Mar. 7, 1944 TIMING APPARATUS ThomasB. Gibbs. Delavan. Wis., assignor, by

assignmen meme ts. to George W. Borg Corporation, Chicago, Ill., acorporation of Delaware Application August 11, 1941, Serial No. 406,350

Claims. (CI. 73-51) The present invention relates in general to timingapparatus, and more in particular to apparatus for timing or checkingthe rate of mechanical fuses such as are used in shells. The object ofthe invention is to produce a new and improved apparatus of thischaracter.

The rate of a mechanical or clockwork type fuse is affected by therotation of the shell in flight and consequently it is necessary to timesuch fuses while they are subjected to rotation simulating the rotationthey acquire when the shells in which they are used are fired. Thiscondition renders the timing of fuses a considerably more dimcultproblem than it would be otherwise. A special object of the invention,therefore, is to provide a new and improved arrangement for obtaining anindication of the rate or beat frequency of a fuse while the same isbeing rotated at high speed. More in detail, the invention provides avariable condenser, one of the elements of which is an oscillatingmember forming part of the clockwork mechanism of the fuse. The capacityof the condenser is varied periodically by operation of the fuse and thevariations in capacity are employed to produce periodic voltages thefrequency of which may be compared with a standard frequency in order todetermine if the rate of the fuse is correct or not.

The invention and various features thereof will be described fullyhereinafter with reference to the accompanying drawing, in which- Fig. 1is a sectional view of a chuck for holding a fuse while it is beingrotated, together with a motor for rotating the chuck and fuse, and adiagrammatic circuit drawing;

Fig. 2 is a top view of the chuck, with the cap removed;

main parts, a receptacle for receiving the fuse and a cap for lockingthe fuse in position in the receptacle. The receptacle part of the chuckincludes a base portion 3 which is suitably fitted to the shaft 2 so asto be rotated thereby when the motor is running. There is also aninternally flanged cylindrical part 0, which is secured to the base 3 bymeans of screws, as shown. The interior wall of the cylindrical part 4is spaced away from the exterior wall of the base 3 to form an annularspace for receiving the open end of the cap 5.

The cap 5 is a cylindrical shell open at the lower end and closed at thetop. The cap is removable from the chuck. When assembled in place, theopen end of the cap enters the annular space between the base 3 and thepart 4, where it is held by a plurality of bayonet joints. One of thesejoints is shown on the section line in Fig. 1, and comprises the pin 6,rigidly fixed.

in the base 3, and the cooperating slot 1 which is cut in the skirt ofcap 5. The shape of the slots can be seen from the dotted line showingof the next adjacent joint comprising the pin 9 and the slot Hi. It willbe understood that in practice there will be three or four of thesejoints, equally spaced around the lower end of the cap 5.

Inside the cap there is a short cylindrical member l2, which is slidableup and down in the cap. The member is urged in a downward direction bythree springs such as 13 and It. a

pin IS, the end of which enters a groove It in member I 2, limits theextent of the downward movement of said member.

A fuse of the type previously referred to is indicated at II. with thecap 5 removed, the

fuse may be placed in the annular seat l8 which is formed at the upperend of the base 3. 'The seat I8 is provided with a projection l9 (seeFig. 2), which fits in a recess 20 in the fuse, and accordingly the fusemust be turned until the recess and the projection are in alignmentbefore it can be properly seated. The arrangement described preventsrotation of the fuse in the chuck and also insures that the fuse will beplaced in the chuck in the correct angular position to bring theelements of the variable condenser into operative relation, as will beexplained shortly.

when the fuse I! has been properly positioned in its seat, the cap 5 maybe put on and is rotated until the pins such as 8 enter the slots suchas It. The upper seat 2| thereupon engages the top of the fuse. The capis now pressed down as far as it will go, the cylindrical member I!moving upward against the tension of springs I 3 and I4, and is thenrotated in the proper direction to eng e the bayonet joints. The cap isthus locked in position and the fuse is securely At the upper end of thebase 3 of the chuck there is a circular recess in which there is mounteda disk 22 by means of screws such as 26. The disk 22 may be of suitablemolded plastic material which is a good insulator and has embeddedtherein a U-shaped metallic member 23. One leg of the member 23 is inthe form of a pin 24 which projects upward a short distanceabove the topof the disk 22. The other leg 25 has its end flush with'the top of thedisk and has a hole drilled through it axially to receive a stiff wire21 which may be a piece of piano wire. The end of wire 21 is secured tothe leg 25 in some suitable manner, as by soldering.

The wire 21 extends downward through the hollow shaft 2 of the motor Iand is supported at intervals by insulators such as 28. The lower end ofthe wire projects into a quantity of mercury 29 which is contained in ametal cup 32; The cup is supported at the lower end of the motor by abracket II, there being a piece of insulating material 30 interposedbetween the cup and bracket. It will be seen that the describedarrangement provides a conductive connection between the pin 24 in thechuck, which is adapted to be rotated by the motor, and the fixed cup22.

The fuse shown in Fig. 3 includes a plate 24 having openings thereinthrough which parts of the clockwork mechanism may be seen. These partsinclude the oscillatable balance or pallet arm 38, the two pallets 26and 31, and the escape wheel 35. When the fuse is running the pallet arm38 oscillates back and forth across the opening 39 in the plate 34. Thepallet arm is shown in its mid-position in Fig. 3, where it appears atthe center of the opening 29. The pin 24 is so located with reference tothe projection l9 (see Fig. 2), that when the fuse is seated properly inthe chuck the pin enters the opening 39 in plate 34 of the fuse. The pin24 does not contact any part of the fuse, being centrally disposed inopening 39, but it is long enough so that its fiat end surface comesclose adjacent to the pallet arm 38. The pallet arm 38 and the pin 24thus form the elements or "plates of an air cbndenser, the capacity ofwhich is variable responsive to oscillation of the pallet arm. Thecapacity is a maximum when the pallet arm is in its midposition and is aminimum when the pallet arm reaches the end of its beat in eitherdirection.

The reference character 42 indicates a space discharge device, which maybe any known tube suitable for use as an amplifier. The circuits of thetube are conventional and need not be described in detail.

The rectangle 50 represents a suitable amplifier which will usually berequired in addition to the amplifying tube 42. The amplifier mayinclude a suitable filter. The rectangle represents a standard frequencysource, which may be of any known and suitable type, such, for example,as a standard frequency generator using a crystal oscillator. Therectangle 52 represents any known type of device, referred to as atimer, which is used to compare the frequency of the current produced bythe fuse with the frequency of the standard frequency source. Theinvention is not concerned with these parts of the equipment andaccordingly they are not shown in detail.

The operation of the invention will now be described. The fuse is placedin the chuck in the manner described and is locked in placed by the cap5. A protective guard or housing for the chuck may be provided and islowered into posi tion around the chuck after the fuse has beeninserted. This guard is not a part of the invention and has accordinglybeen omitted. The motor I has circuit connections, also not shown, to asuitable source of alternating current.

When the power is turned on the motor starts to run and comes rapidly upto speed, rotating the chuck and the fuse which is held therein. Thefuse is provided with a pair of pivoted weights which are acted on bycentrifugal force while the fuse is rotating and supply power foroperating the clockwork mechanism. Accordingly the pallet arm 38 in thefuse starts to oscillate in the manner previously described.

Thevariable condenser formed'by the pallet arm and the pin 24 isincluded in a circuit which extends from ground by way of the frame ofthe motor, the chuck, the body of the fuse, the oscillating pallet arm,the pin 24 (separated from the pallet arm by a varying air gap), member22, wire 21, mercury 29, cup 32, conductor 40, and resistance 4i to thegrounded battery B. The condenser charges and discharges over thiscircuit as its capacity varies responsive to the oscillation of thepallet arm 38, and accordingly variations in potential are produced atthe junction point 43, which are applied to the control grid of tube 42through the condenser 44. These potential changes produce plate currenfluctuations at the tube 42 and amplified potential changes at the plateof the tube, which are transmitted to the amplifier 50 by way ofconductor 45.

The output frequency of tube 42 corresponds to the beat frequency of thefuse, as will be appreciated from the fact that the capacity of thecondenser formed bythe pallet arm 38 and the pin 24 rises from a minimumto a maximum and decreases to a minimum again during each beat of thepallet arm. If the beat frequency of the fuse is 344 beats per second,therefore, the output of tube 42 will have a frequency of 344 cycles persecond, and for any departure of the beat frequency of the fuse from itscorrect value there will be a corresponding departure in the outputfrequency.

The output of tube 42 may be further amplifled at the amplifier 50, ifnecessary, and the output of the amplifier is transmitted to the timer52, where its frequency is compared with the standard frequency. Thetimer may be of any suitable type, as previously mentioned, and if amechanical timer is employed the amplifier equipment 50 will includesuitable means for converting the amplifier output into impulses of theproper character to operate the timer. However, a very simplearrangement is to use a cathode ray oscilloscope as a timer. In thiscase the amplifier 50 supplies the fuse signal frequency to one pair ofdeflecting plates in the cathode ray tube and the standard frequencygenerator supplies sweep frequency to the other pair of deflectingplates. The use of a cathode ray oscilloscope for comparing frequenciesis I well known and hence need not be described in detail.

From the foregoing it will be seen that the invention provides a simpleand efiicient apparatus for use in regulating fuses, whereby signalcurrents 'or voltages having a frequency corresponding to the beatfrequency of a fuse may be obtained while the fuse is rotating, thusenabling the rate of the fuse to be determined by comparison of thesignal frequency with a standard frequency.v

The modification which is shown in Figs. 4 and 5 involves a change inthe location of the pin which cooperates with the oscillating pallet ofthe fuse to form a variable condenser. In Fig. 5, the pin is indicatedat 24'. As can be seen from this figure, the pin 24' isangularlydisplaced in a counter-clockwise direction from the positionoccupied by pin 24 in Fig. 2. The fuse is partly shown in Fig. 4, fromwhich it can be seen that the opening 39' is elongated on one sideinstead of being round. When the fuse is inserted in the chuck, the pin24' enters the opening 39' where it occupies a position near one end ofthe opening, as indicated by the dotted circle 24'. Inthis position thepin is overlapped by the oscillating pallet 38' at the extremity of itsbeat in a clockwise direction, as seen in Fig. 4. At the end of thisclockwise beat, therefore, the capacity of the variable condenser is amaximum. On the counter-clockwise beat the capacity decreases andreaches a minimum at the end of the beat, when the pallet is at thegreatest distance from the pin. Two beats are required, therefore, toproduce a complete cycle of capacity change in the condenser, and theoutput frequency is equal to one-half the beat frequency. Otherwise theoperation is the same as previously described.

The invention having been described, that which is believed to be newand for which the protection of Letters Patent is desired will bepointed out in the appended claims.

I claim:

1. Apparatus for timing a device having a part which is subjected tooscillatory motion, comprising means for rotating said device, means forforming a variable condenser including said part as an element andhaving a capacity which is varied by oscillatory motion of the partwhile said device is rotating, and means responsive to variations in thecapacity of said condenser for generating periodic voltages.

2. Apparatus for timing a fuse of the clockwork type having a partsubject to oscillatory motion, comprising means for rotating said fuse,a condenser including said part the capacity of which is variable byoscillatory motion of said part while the fuse is rotating, and meansresponsive to variations in said capacity for generating periodicvoltages.

3. Apparatus for timing a fuse of the clockwork type having a partsubject to oscillatory motion, comprising a chuck for holding said fuse,means for rotating said chuck and fuse, an insulated part mounted onsaid chuck and located adjacent the said oscillatory part of the fusewhen the fuse is held in the chuck, said parts forming a variablecondenser, and means responsive to variations in the capacity of saidcondenser produced by the oscillatory motion of the said fuse part forgenerating periodic voltages.

4. The combination, with means for operating a fuse of the clockworktype by subjecting to rotation, of a conductive member, means forsupporting said member in spaced relation to an oscillating part of saidfuse while the fuse is in operation to form a variable condenser, and acontrol circuit including said condenser.

5. The combination, with means for operating a fuse of the clockworktype by subjecting it to rotation, of a conductive member, means forsupporting said member in juxtaposition to an oscillating part of saidfuse while the fuse is in operation, thereby forming a condenser thecapacity of which varies responsive to operation of the fuse, meansresponsive to the capacity variations of said condenser for generatingperiodic voltages, and means for comparing the frequency of saidvoltages with a standard frequency.

6. In a fuse timing apparatus, a rotatable chuck comprising means forholding a fuse, a part mounted on said chuck and forming a variablecondenser with an oscillatory part of a fuse which is held in the chuck,a space discharge device, and a circuit over which said condensercontrols said device while the chuck and fuse are rotating.

7. In a fuse timing apparatus, a rotatable chuck comprising means forholding a fuse, means for forming a variable condenser with anoscillatory part of a fuse held in the said chuck, the variation in thecapacity of said condenser being responsive to the oscillatory motion ofsaid part, a source of current for charging said condenser, and acircuit including said condenser, said current source and the frame ofthe fuse and chuck.

8. In a fuse timing apparatus, a rotatable chuck comprising means forholding a fuse, an insulated part supported on said chuck and forming avariable condenser with a part of the fuse which is subjected tooscillatory motion when the chuck and fuse are rotating, and means forconnecting said condenser in an external circuit.

9. In a fuse timing apparatus, a rotatable chuck comprising means forholding a fuse, an insulated part supported on said chuck andcooperating with an oscillatory part of the fuse to forin a variablecondenser, a source of current for charging said condenser, a circuitincluding said condenser and current source, and means for maintainingsaid circuit closed while said chuck is rotating.

10. Apparatus for timing a fuse having a part subject to oscillatorymotion, comprising a chuck for holding said fuse, a motor for rotatingsaid chuck, said motor having a hollow shaft, an insulated partsupported on said chuck and located adjacent said oscillatory part ofthe fuse when the fuse is held in the chuck, said parts constituting acondenser the capacity of which is variable responsive to oscillatorymotion of said fuse part, an insulated conductor connected to the saidpart supported on the chuck and extending through the motor shaft, and acircuit including said condenser and conductor.

11. In a fuse timing apparatus, a rotatable chuck comprising means forholding a fuse, and an insulated conducting part mounted on said chuckin such a position that when a fuse is held in the chuck the said partcooperates with an oscillatory part of said fuse to form a variablecondenser.

12. Apparatus for timing a device having an oscillatory pallet,comprising a conductive member, means for supporting said member in sucha position relative to the device that the member is juxtaposed to thepallet when the latter is in mid-position, thereby forming a condenserthe capacity of which is varied at each beat of the pallet, and meanscontrolled by said condenser for generating periodic voltages having afrequency equal .to the beat frequency of the pallet.

13. Apparatus for timing a device having an oscillatory pallet,comprising a conductive member, means for supporting said member in sucha position relative to the device that the memholding a fuse, means forrotatingsaid chuck, a 10 circuit including an insulatecLconductorrotating with the chuck and a fixed conductor in electrical contacttherewith, and means including an oscillating part of a fuse held insaid chuck while the same is rotating tor periodically varying a 1characteristic oi said circuit.

15. Apparatus for timing a device having a part subject to periodicmotion while the device is being rotated, comprising means for rotatingsaid device, means for forming a variable condenser with said part, thevariation in the capacity of said condenser beinx responsive to theperiodic motion of said part, a source of cur rent, and a circuitconnecting said condenser and current source, said circuit including aslip connection comprising a rotating part in conductive connection withsaid condenser and a iixed part in conductive connection with saidcurrent source.

THOMAS B. GIBBS.

